Spring has finally sprung, and with it, as common a sound as the chirping of migratory birds, is this cry heard in and around fitness centers everywhere: “Time to start working on that swimsuit bod!”

As much as I fantasize about sitting on people who say things like that, I must admit that the comfort food that sustained me in January perhaps wasn’t as requisite to survival as it had seemed at the time. And even though I can’t recall putting on a bathing suit once last summer, it’s not like I wouldn’t mind having a swimsuit bod.

And that’s why, earlier this month, I dug my spandex pants out of storage and dragged myself to Studio Zenith on Montpelier’s Main Street for a class called Vigorous Hatha Yoga. I’ll admit, the word vigorous gave me and my underworked muscles a momentary panic attack, but the course description set me at ease: “The physical challenge of sustained holds, twists, lifts and breath work together to steady the mind and invigorate the body.” I thought, “How vigorous can twisting and breathing be?” This sounded like little more of a challenge than my favorite wintertime pose, sitting on the couch and downloading episodes of Downton Abbey.

Even so, I implored the instructor, Chaya, to go easy on me. She flashed a sympathetic smile and then proceeded to twist me and my classmates into poses so completely opposite of curling up on the couch that my muscles begged for mercy. At the end of the class, I was sweaty, sore, and completely energized. Furthermore, I was so dazzled by the skills exhibited by my classmates that I promised myself to make more time for yoga. I desperately wanted to fly like the others had in crow pose and lift into warrior; or at the very least, touch my heels to the ground in downward dog.

And that, as it happens, is exactly the kind of experience studio owner Amy Leventhal wants for her students. None of the courses offered at Zenith — not even Boomer Yoga, a gentle class for seniors and injured athletes — are supposed to be easy. “The studio is all about getting your strongest and fittest, to live your happiest life and to really keep pushing it,” said Leventhal, who instructs her crew of trainers to teach to the more advanced level and offer modifications for beginners. “This gives students a chance to see people who are upside-down with their feet behind their heads on one finger,” she explained, “but at the same time they can just do a basic hip stretch.”

When the space opened last fall, I assumed it was just another yoga studio, as common a sight in Central Vermont as fast food chains are in other parts of the country. At a glance, Zenith looks like any self-respecting yoga studio should: an empty room with a clean hardwood floor, a few potted plants and candles, and tall mirrors on one side.

But a more thorough investigation of the space will reveal that the back corner is stocked with weights, kettlebells, and other equipment one might find in a gym. In the past six months, I’ve walked past the glass entryway dozens of times and rarely seen the same thing happening inside twice. Some days I peer in and see bodies stretched out on yoga mats, but just as often the classroom is full of steely eyed kickboxers jumping up and down into pushups and pumping urgently at the air.

Even on the days when I walk by as students are lunging and hefting weights out of their own sweat puddles, the fact remains that Zenith looks and feels more like a yoga studio than a gym. This is no accident, as Leventhal hates gyms. “I don’t like big, open, cold spaces with machines blasting music and TVs. I wanted this studio to be as little like a gym as possible,” she said. Indeed, whereas I’m usually anxious to outperform everyone whenever I exercise around people, in my class at Zenith I felt relaxed and uncompetitive.

As a yoga studio with a gym-like flair, Zenith’s course offerings are as diverse as the abilities of its students. So even if your driving focus isn’t to fit into that teeny-weenie-itsy-bitsy yellow polka dot bikini by summer, it’s well worth a visit.

Here’s a small sampling of the many classes available this spring at the studio.

High Intensity Interval Training — This is pretty much what it sounds like: a fast-paced class designed to build muscle, and — you guessed it — tone and tighten that swimsuit bod. In between 20- to 40-second intervals of weights, burpees, mountain-climbers, and other hard work, students get 10 seconds of “rest” (if you can call it that) in which they perform pushups or lunges.

Yoga for Kids — What parent in his or her right mind wouldn’t want to drop off the kids on Mondays at 4 p.m. for an hour of playful self-expression? This course features valuable skills for all children ages three to 12, from building social skills to balancing postures and sitting perfectly still.

Karate Interval Cross Training — A total body workout inspired by martial arts. The course description on the web calls it a “perfect mix of pleasure, pain, excitement, camaraderie, and challenge!” Who can say no to that?

Ashtanga Yoga — A series of about 75 poses, including sun salutations, standing and seated poses, inversions, and backbends. Zenith is the only studio that offers Ashtanga in Montpelier, and currently it’s the most popular class at the studio.

Boomer Yoga — The name refers to the baby boomer generation but this course is a good fit for injured athletes or anyone with a limited range of motion. Be warned, however, that this is no “Yoga for Slackers,” since course instructor Chrissy Lefavour does not intend for it to be easy. “After every class, someone always comes up and says, ‘That was harder than I thought it was going to be,’” she said.

Marija Zagarins is a writer from Montpelier. Her column, Found Downtown, focuses on independent businesses around central Vermont.